Characterization of Pink Pigmented Facultative Methylotrophs (PPFMs) from Palm oil (Elaeis guineensis) Leaves

Methylobacterium strains are ubiquitous in the environment especially in the phyllosphere of plants. Four Methylobacterium strains have been isolated previously; EPPM1 (Unidentified), ENPM1 (Methylobacterium radiotolerans),ENPM (Methylobacterium aeroletum), and ENPM3 (Methylobacterium radiotolerans). All four strains were characterized to determine their ability in promoting the plant growth for significant use in biofertilizer. The microbes with plant growth promoting (PGP) attributes have emerged as an important and promising tool for sustainable agriculture. The evaluation of the production of Indole acetic acid (IAA) by Methylobacterium sp. indicated the isolates can produce IAA by using different concentrations of L-tryptophan as a precursor. In addition, IAA production rate of isolates increased with the increasing concentration of L-tryptophan. The ability of nitrogen fixation by Methylobacterium sp. isolates was determined using a qualitative technique on two different medium; Burks’s and Jensen resulted three of the selected isolates (ENPM1, ENPM2, ENPM3) able to fix nitrogen. The determination of phosphate solubilization by Methylobacterium sp. Isolates was done using two types of medium; NBRIP and Pikovskaya’s. Measurement of Solubilization Index (SI) on agar plate showed that ENPM1, ENPM2 and ENPM3 strains have the ability to perform phosphate solubilization activity using inorganic TCP. Phosphate assay was done using vanadate molybdate reagent using inorganic TCP. All four isolates have ability to solubilise inorganic phosphate and EPPM1 recorded the highest capability in NBRIP and Pikovskaya’s broth followed by ENPM3, ENPM2, and ENPM1. Solubilization of inorganic phosphate in Pikovskaya’s showed a higher value in all isolates compares to NBRIP. So the Methylobacterium sp. strains analysed had a promising potential as plant growth promoting bacteria and be used as biofertilizer.